High voltage ignition system



May 20, 1958 R. MOREL 2,835,850

HIGH VOLTAGE IGNITION SYSTEM Filed Aug. 5, 1954 2 Sheets-Sheet l INVENTOR ROGER. -MOREL BY M ATTORNEY May 20, 1958 R. MOREL 2,835,850

HIGH VOLTAGE IGNITION SYSTEM Filed Aug. 5, 1954 2 Sheetg-Sheet 2 1N VENTOR ROGER MORE L ATTORNEY United States Patent 0 F HIGH VOLTAGE IGNITION SYSTEM Roger Morel, Grenoble, France, assignor to Societe Anonyme de Machines Electrostatiques, Grenoble, France, a corporation of France Application August 5, 1954, Serial No. 448,085

Claims priority, application France August 5, 1953 20 Claims. (Cl. 315-180) This invention relates to ignition systems, especially to systems for ignition of combustible gases and vapors by means of an ignition device or spark plug requiring a high electrical potential. The invention particularly relates to such ignition systems for internal combustion engines.

Ignition of charges of fuel in an internal combustion engine involve problems relating to the precision of timing of the spark, insulation difliculties, fouling of the ignition devices or spark plugs, capacitive and inductive losses and other conditions. Especially in automotive vehicle engines these difliculties are aggravated because ignition may be required to be effected at low temperatures, particularly at starting in cold weather. In such engines with very high compression ratios, high engine speeds and a large number of cylinders the conventional ignition systems using an electromagnetic inductive device or spark coil to supply the high potential may function unsatisfactorily or not at all under such adverse con ditions.

In the endeavor to meet the above mentioned conditions it has been proposed, heretofore, to utilize capacitive discharge. The very short duration of such capacitive discharge atfords the possibility of insuring correct ignition and improved efiiciency under conditions where electromagnetic inductive ignition would be unsatisfactory. Certain systems which utilize the conventional battery and vibrator are limited with respect to the potential capable of being developed because it is ditlicult to obtain higher potentials by the means proposed in connection with a battery ordinarily of six to twelve volts. The distributor which also serves for timing the ignition operates in air at ordinary pressures and under these circumstances the precision of the timing of the ignition becomes reduced at higher potentials so that about 5,000 volts is the maximum which may be developed with such a capacitive system as heretofore proposed. it is also difficult to maintain the proper insulation for continuous high potential under conditions of humidity and dust. Insulation which may be sufficient for instantaneously applied high potentials may not be suflicient if such high potential is continuously developed.

With the purpose of improving the conditions referred to in some capacitive systems special spark plugs have been utilized which, in additionto being fragile and expensive, are not entirely suitable for starting, particularly at low temperatures. With a view to utilizing conventional'spark plugs, transformers individual to the spark plugs or a step-up transformer developing the high potential to be distributed have been proposed in order to increase the applied voltage with the disadvantage of introducing additional inductive losses. It has been found that much higher voltages than 5,000 are required to secure the desired improvement with capacitive discharge. A generator of such higher voltages involves special design of the apparatus. An electrostatic generator, however, capable of generating a capacitive charge at poten- 2,835,850 Patented May 20, 1958 tials of the order of 25 kilovolts has been developed and utilized without a coil or step up transformer and supplying conventional spark plugs. The desired precision of discharge and distribution of the charge to the spark plugs has been secured with this generator operating in a pressurized casing at 10 to 20 atmospheres.

It is an object of the present invention to provide an improved ignition system capable of securing highly satisfactory conditions of capacitive discharge and which may be utilized in connection with spark plugs and certain other elements of the kinds used in conventional ignition systems for internal combustion engines, particularly engines of automotive vehicles.

The system of the invention comprises a voltage multiplier having a plurality of capacitors, these capacitors being utilized to provide the capacitive charge which is to be delivered to the spark plugs. The voltage multiplier for this purpose may be of the form disclosed in the German patent to Marx No. 455,933 of February 13, 1928, in which the capacitors are connected in parallel across a source of given potential for charging these capacitors at this given potential. In accordance with the principle embodied in the Marx multiplier, means are provided for effecting discharge of these capacitors in series with each other, thereby to multiply by the number of capacitors the' given potential initially applied to each of the capacitors. In order to maintain the electrodes or plates of the capacitors insulated from each other during charging and at the same time to provide for discharge in series, a device, such as a spark gap element, is connected between each two adjacent capacitors and the discharge of the capacitors in series is eifected through this series of discharge devices or spark gaps. To prevent the short circuiting of the capacitors upon operation of the spark gaps the resistance of which is very low upon breakdown, resistors are connected in series with the source of given potential and the parallelly connected capacitors are connected across this source at points spaced along these resistors.

In accordance with the invention the multiplier referred to may be supplied from a generator developing the given potential of less than 5,000 volts, for example 2,000 to 3,000 volts as a unidirectional potential, or it may be supplied from the secondary of the conventional spark coil or other transformer capable of developing the given potential in connection with a rectifier. The spark coil may be energized by connecting its primary coil across a low potential, for example that of a battery. This primary coil may be connected in the conventional manner with the usual make-and-break device for in ducing an oscillating current in the primary and the corresponding oscillating potential in the secondary of the coil at the given potential.

Within the scope of the invention the conventional distributor disposed in the circuit supplying a plurality of ignition devices or spark plugs may be utilized. Even though designed for the given potential of less than 5,000 volts, because of the instantaneous capacitive discharge this same distributor may serve in the system of the invention when subjected to the multiplied voltage, or if desired a distributor designed for high potential may be used. The movable member of this distributor which is brought successively into circuit closing relation tothe' stationary electrodes of the distributor that are respectively connected to the spark plugs is connected in series with the group of parallelly connected capacitors of the voltage multiplier and the series discharge of these capacitors to the respective spark plugs is effected in succession through this member.

It is one of the important features of the invention that initiation or triggering of the discharge in series through'the capaictors to the spark plugs may be ac complished in various simple ways and under positive control. Such triggering may, for example, be secured by means of a device which is connected in series between two adjacent capacitors, this triggering device providing an elementwhichis movable into and out of circuit closing relation to an auxiliary electrode, preferably at spark gap distance from such electrode, to effect across this spark gap the initial discharge which triggers the series discharge of the remaining capacitors under the multiplied potential secured by the connection of these capacitors in series.

Triggering alternatively may be accomplished by variation by suitable mechanical means of the spark gap of one or more of the spark gap elements of the voltage multiplier. Within the scope of the invention also fixed spark gaps may be used in the respective spark gap elements, one of which, however, may have a shorter spark 'gap than the others for triggering purposes. The triggering of the discharge then may be accomplished by sufficient increase by suitable control means of the given potential across which these spark gap elements are connected in the voltage multiplier to effect an initial breakdown of the short spark gap and the triggering of the series discharge.

It is a further feature of the invention that the triggering device may be constructed and operated to etfect the triggering in synchronism with the distributor supplying a plurality of ignition devices or spark plugs and that this synchronized triggering device may be driven by the same means, for example the distributor spindle, by which the distributor is driven from the internal combustion engine. As in conventional systems the distributor may operate in air at atmospheric pressure or, if desired. a pressurized distributor may be used for more precise discharge at high potential. 'In the system of the invention the triggering under the given potential may be effected at atmospheric pressure.

Whatever generating means may be used to generate the given potential, it is a significant feature of the invention that this potential may be a relatively low or medium potential as compared to the very high potential, say of the order of 25 kilovolts, that is required in producing the capacitive discharge requisite for efficient operation of the ignition system. The use of a voltage multiplier of the type described in the igniton system provi'des not only the requisite capacitance but also the desired step-up from the given potential to the ignition potential. In the system of the invention the build-up of the capacitive charge and its discharge at high potential is also effected over an extremely short time period, much shorter than the time interval between the successive firings of the sparkplugs in an internal combustion engine whatever may be the number of cylinders and the speed of the engine.

After the series discharge of the capacitors occurs, the new build up of the charge on the parallelly connected capacitors may start immediately and develop rapidly because these capacitors are continuously connected across the given potential, there being no inductive loss and no voltage drop along the resistors when the series circuit is opened upon cessation of the series discharge. Thus, the provision of the voltage multiplier of the type described in an ignition circuit supplying a plurality of spark plugs from the source of given potential makes this circuit highly suitable for supplying the requisite high potential as a capacitative charge to a large number of spark plugs in rapid succession, for example, in an engine with a large number of cylinders, as well as for supplying this high potential to the spark plugs of an engine operating at high speed. The time required for charging the capacitors may be much less than a few thousandths of a second and the values of .the' resistance of the resistors across which the capacitors are'connecte'd may be suitably determined in relation to the capacitances to provide a wave-front of the discharge wave which is sufiiciently 4 steep so as not to develop large ohmic losses during discharge. During the relatively long period between successive discharges to the ignition devices the potential to which the system is subjected is not greater than the given potential generated by the generating means.

It will be understood, therefore, that the potential to which the parts of and the connections to the voltage multiplier normally are subjected is the given potential rather than multiplied or high potential desired to be supplied to the ignition devices. This high potential is developed at the instant of discharge, however, and the multiplier and distributor and other parts subjected to this multiplied potential require generally only the same conditions as to insulation and construction of the parts that are necessary for the distributor in a conventional ignition system because these parts are subjected to the high potential only for very short intervals. Moreover, the triggering" device may be disposed so as to be subjected to a potential of the degree of the given potential and not to the multiplied or high potential. This is the case also with respect to the normal potential difference across the individual spark gap elements that are respectively connected between the capacitors. Nevertheless, the advantages above referred to of capacitative dis charge are secured whether a generator itself developing the given potential is provided or a conventional spark coil is utilized or, on the other hand, a so-called vibrator which itself makes and breaks the circuit through its coil is connected in the well known manner to secure the oscillating potential having peaks of sufliciently high potential for ignition purposes.

It is an advantage of the invention that the system may be used for ignition of internal combustion engines of any of the usual number of cylinders by utilizing a synchronized triggering device having the proper number of electrodes corresponding to those provided in the distributor for such an engine, the remainder of the system, including the portions of the conventional system that are utilized, being arranged as above described. This. triggering device advantageously may be housed in the same housing as the distributor. The voltage multiplier also may be combined with the distributor-triggering unit or may be combined with the unit generating the given potential.

The conventional means for advancing the spark may be used, the triggering device being disposed in such relation to this means and the distributor that synchronism of triggering with the distributor is maintained.

The features and advantages of the invention in certain embodiments thereof will be more fully described in connection with the drawings in which:

Fig. 1 shows an ignition system including a voltage multiplier and a synchronized triggering device;

Fig. 2 shows a modification of the ignition system of Fig. l utilizing a plurality of synchronized triggering devices;

Fig. 3 shows an ignition system utilizing a voltage multiplier in connection with a conventional spark coil and a make-and-break device;

Fig. 4 shows a further modification of the system wherein the generator of low voltage is omitted and the voltage multiplier is charged through the medium of a transformer and with utilization of a storage capacitor and a rectifier.

In Fig. l the generator 1 is designed to develop a direct current potcntialof the given value, preferably of the degree of 2,000 to 3,000 voits. This generator may be driven through the shaft 3 which may be connected through a suitable drive to the drive shaft of an internal combustion engine. In parallel with the generator as an alternative source of the given potential, the vibrator 5 may have its primary coil connected in series with thebattery 7 and with its armature 4 and contact 6. Switch '8 in the connection from the secondary of the vibrator 5 and switch 9 in the connection from the generator are provided for selecting one or the other of these sources of given potential to be connected to 'the voltage multiplier. A condenser is connected across the contact 6 and armature 4 for minimizing the sparking in the usual manner. It will be understood that the alternative source of a given potential has been shown in Fig. 1 merely by way of illustrating that the given voltage may be provided in various ways without necessarily modifying the other elements of the system and to reduce the number of drawings. Ordinarily only one of the two given voltage sources need be incorporated in a particular embodiment of the system.

As shown in Fig. 1 the voltage multiplier is of the Marx type and comprises a plurality of capacitors 11, 12, 13, 14, and 16 which are connected in parallel across the source of given potential. In the embodiment of Fig. 1 these capacitors, have their terminals connected at points spaced along resistors 19 and 21mm are connected to the respective sides of the source. Have ing regard to the fact that a direct current potential is applied to this multiplier by the generator or by another conventional source and that during the period between the discharge intervals no current flows through these resistances because of the intervention of the capacitors, the potential of the respective sides of the source is provided at all points along the resistors 19 and 21 so that the capacitors are charged at the given potential in parallel.

As shown in Fig. 1, means are provided for effecting connection of the capacitors 11 to 16 inclusive in series for discharge of these capacitors. This may be accomplished, as shown, by the interposition of spark gap elements 23, 2s, 25 and 26 between adjacent capacitors, these spark gap elements respectively being connected between the terminal of a capacitor connected to one side of the source, for example, the resistor 21, and the terminal of the adjacent capacitor that is connected to the other side of the source, that is to the resistor 1). When, because the potential of the source is raised or because the spark gap of one or more elements is reduced, or by operation of a triggering device the potential across a spark gap exceeds that of its breakdown potential, discharge takes place acrossthe spark gaps between the adjacent capacitors, the charge carried by the assembly of capacitors in effect being discharged in series through the spark gaps and through the capacitors, the potential difierence across the thus series connected capacitors at that moment being equivalent to the given potential applied across the parallelly connected capacitors multi plied by the number of capacitors in series in accordance with the well known capacitance principle.

As is well known, the resistance of the spark gaps is very low when discharge takes place. The resistance represented by the sections of the resistors 19 and 21 between the points of connection of the capacitors thereto may be made very large to prevent short circuiting of the discharge and to insure discharge in series through the capacitors while also insuring that the given" poten tial initially shall be applied to all of the capacitors in their parallel connection. Although the theoretical resistance for maintaining the proper given potential and preventing short circuiting of the capacitors on discharge is of the degree of one megohm in a system suitable for internal combustion engine ignition, in practice it is found that resistors of much less resistance may be used. For the multiplier of Fig. 1 supplied at 2,000 to 3,000 volts the several sections of the resistors 19, 21 connected between terminals of the capacitors which are connected to these resistors may be of the degree of 10,000 ohms to 100,000 ohms. The wavefront of the potential developed by the voltage multiplier with such resistors of lower resistance value may be sufficiently steep so that the ohmic loss through these resistances on discharge is not excessive.

6 by the lead 30 to the movable distributor. arm 31 which is driven by the shaft 33 which may be connected to the engine shaft by conventional kinematic means to rotate at one-half of the engine speed for a four cycle engine.

As in conventional systems, the distributor in the embodiment of Fig. 1 provides four fixed electrodes 35 respectively connected to spark plugs 36 for firing the cylinders of a four-cylinder engine. Such firing takes place when the rotating arm 31 of the distributor moves into circuit closing relation to, preferably at: spark gap distance from, the fixed electrodes 35 upon rotation of the shaft 33. Upon discharge of the multiplier the higher potential developed by this multiplier, that is the given potential multiplied by six in the embodiment of Fig. l, is applied to the distributor arm 31 and to the respective spark plugs 36 connected respectively to the fixed electrodes 35. In the embodiment shown in Fig. 1 utilizing six capacitors the multiplied or high potential will be of the degree of 18,000 volts when the given potential is 3,000 volts. By utilizing a larger number of capacitors, for example, eight capacitors, this voltage may be increased to 24,000 volts; or ten capacitors supplied at 2,000 volts would provide 20,000 volts.

As shown in Fig. 1 the spark gap element is omitted between the first two capacitors 11 and 12. In its place a synchronized triggering device 40 is connected across the terminals of the capacitors 11 and 12 in the same manner as the spark gap elements 23 to 26 inclusive. The synchronized triggering device 40 comprises an element 41 carried by the shaft 33 and rotatable therewith into circuit closing relation to a plurality of fixed auxiliary electrodes 43, these electrodes 43 all being electrically connected together and connected to the terminal of the capacitor 12 which is connected to a given side of the source, that is, to the resistor 21. The rotatable element 41 is connected to the terminal of the capacitor 11 that is connected to the other side of the source, that is to the resistor 19. The electrodes 43 are disposed about the axis of the shaft 33 in angularly spaced relation to each other corresponding to the angular spacing of the electrodes 35 of the distributor. Thus, the rotatable element 41 may be in register with an electrode 43 simultaneously with registration of the arm 31 of the distributor with a fixed electrode 35 of this distributor. The rotatable element 41 may make contact in succession with the electrodes 43 but preferably moves into and out of register with the respective electrodes 43 at such spark gap distance that the potential between the two resistors 19 and 21, is sufficient to develop breakdown of the spark gap between the element 41 and each electrode 43 when in register therewith. Such breakdown effects movement of the charge on the capacitor 11 and modification of the potentials in the series connected capacitors and spark gaps so that with a suitable setting of the spark gaps in the spark gap elements 23 to 26 inclusive series discharge takes place through the multiplier to discharge the capacitors through the distributor to the spark plug connected to the particular fixed electrode 35 which is in register with the rotatable arm 31.

The spark gaps 23, 24, 25 and 26 are adjusted so that normally they do not break down under the potential applied across them from the source of given potential. They may be adjusted, however, so that they will break down at a potential in the range between the given potential and a potential equivalent to twice the given potential. This adjustment of the spark gap distance of the spark gap elements may be made having regard to the given potential, to the number of spark gap elements utilized and to the spark gap of the triggering device 40.

According to another embodiment of the invention as shown in Fig. 2 additional mechanical devices similar As shown in Fig. 1 the voltage multiplier is connected 7.5 to the synchronized triggering device 49 may be utilized in substitution for one or more of the spark gaps 23 to 26 inclusive. When a plurality of such triggeringdevices is used only the fixed spark gaps of the upper or higher potential stages need be set to respond to higher potentials, for example, potentials three to four times as great as. the given'charging voltage. These additional triggering devices, one of which is shown at' 44, function in the same manner as the synchronized triggering device 40'and have rotatable elements 45 carried on the shaft 33" either in aligned or in angular relation to the element 41 along the shaft, fixed auxiliary electrodes 47 corresponding to fixed auxiliary electrodes 43 being disposed about the shaft similarly to the electrodes 43 and in such angularly spaced relation to each other and to the electrodes 35' and in such predetermined spark gap relation to the rotatable element 4-5 that when the element 45 is in register with respective auxiliary electrodes 47 spark discharge takes place between the respective elements 45 and the corresponding electrodes 47. It will be understood that the elements 45 and the electrodes 4-7 function in precisely the same manner as the spark gaps 23 to 26 inclusive for which the second and additional synchronized triggering devices may be substituted to produce the series discharge of the capacitors to the spark plugs.

It will be apparent that during charging and in the intervals between discharge the synchronized triggering devices are subjected only to the given potential so that these devices may operate at atmospheric pressure, while securing the very. much increased potential and capacitative discharge from the voltage multiplier through the distributor to the ignition devices.

As an example typical of conditions met in ignition of internal combustion engines and of the results obtained with the system of the invention, it has been found by experience and investigation that the quantity of energy per spark suitable for ignition of an internal combustion engine operating at 5,000 revolutions per minute may be of the degree of 1.2 microcoulombs per spark. In a four cylinder engine at this speed, the distributor shaft operating at 2,500 revolutions per minute, the following calculation develops the amount of power requisite for proper ignition.

Revolutions per second of the distributor=4;l.7

Spark per second=167 (4 cylinders, l point distributor) Microcoulombs per second=l07 l 2:200

W :work

Q quantity of charge V=voltage-using l capacitors in series at 2,000 volts W QV lX =2.0 joules per second =2.0 Watts For. the purposes of such an ignition system ten capacitors eachhaving a capacitance of 600 picofarads operating at 2,000. volts given potential may be used to produce an equivalent capacitance of 60 picofarads:

60 farads X 20,000

200 coulombs per second 20,000 volts 1,000,000

QZCV 1,000,000,000,000

1.2 1,000,000 couomb =12 rnieroeoulomb as above indicated 1.2 3oule If this energy is dischargedin second:

Having regard to losses in the resistors and in capacity effects and other causes it is found desirable to provide a generator or other source of given potential capable of developing aboutv five watts. With the resistors of reduced resistance value above referred to, a ten fold increase of speed or ten times as many cylinders may be suppliedwitlia generator of such larger capacity.

In another arrangement six capacitors each have a capacitance of 360 picofarads and operating at given potential of 3,000 voltsmay be used, the equivalent capacil'ance of the multiplier also being picofarads and the high voltage 18,000 volts.

it will be understood that either with the single synchronized triggering device of Fig. l or a plurality of sch devices respectively connecting adjacent capacitors in series for effecting the series discharge, the triggering of the discharge of the multiplier is effected with, great precision even at very high speeds of the engine. lt also will be understood that, although the potentials with respect to groundpotential to which the respective spark gap elements or the triggering devices substituted there for are subjected are greater for those capacitors which are closer to the discharge connection 30, only those spark gap elements or the substituted triggering devices adjacent this end of the multiplier would be subjected to and would be required to insulate these high potentials and then only at the time of and for the short duration.

of breakdown depending upon the number of capacitors utilized and connected in series with each other upon such breakdown. Since all of the moving mechanical parts, such as those carried on the shaft 33, are in uniform rotation, the precise timing of the breakdown initiated by the synchronized triggering device or devices is secured even at maximum engine speed where the charging time. constant, that is the time available for charging the capacitors, is only a few milliseconds or less. NCVEYlZhG. less, because of the Waveshape of the capacitive charge build up and discharge attainable with the voltage multiplier used in the invention having a time interval which may be of the degree of l or 2 microseconds, the desired precision of timing in an ignition system at high potential is secured without insulation difiiculties.

In Fig. 3 a modification is shown in which the triggering of the voltage multiplier is accomplished by means forming part of a conventional ignition system, including a spark coil and a make-and-break device. In the embodiment of Fig. 3 the given potential generator 1 may be connected to the portion 51 of the resistor 19 of the voltage multiplier through connection 52. A switch: 53. is shown for connecting and disconnecting the generator 1. from the voltage multiplier if for any reason this should be desired. In this embodiment the battery 7 may be connected through a switch 55 to the primary 57 of a conventional spark coil having a secondary 59. Also, connected to the primary 57 and the battery 7 a conventional generator 61 may be provided for charging the battery, a switch 63 being provided for disconnecting this generator from the coil and the battery, if desired. This generator 61 may be driven by an extension of the shaft 3'which1 drives the generator 1 in the same manner as shown in Fig.1.

The primary 57 and the secondary 59 of the coil are connected together at one side thereof and connected through the resistance 65 to the hinge point 67 of the make-and-break blade 69 moved by rotation of the cam 71 into and out of engagement with the fixed contact 73' which is connected to ground in a conventional'manner;

The earn 71 is carried on the shaft 33 driving the dis-.-

tributor arm 31 into register in succession with the stationary electrodes 35' as described. in connection with Fig. 1, these electrodes 35 being connected to the: reespective spark plugs 36, and actuates-the make-and-break.

contact in synchronism with. the distributor arm 31.

When switch 55 is closed, the circuit from the battery 7' is. completed through the primary 57 of the coil and through the resistance 65 to the make-and-break device 67, 69, 73 and thence though ground to the ground connection of the battery.

Energizing the primary of the coil, accomplished in this manner or by the potential generated by the generator 61 alone or in parallel with the battery, develops the energization of the secondary coil 59 each time that the circuit through the primary coil 57 is broken by the make-and-break device 69, 73. The potential thereby developed in the secondary 59 may be applied to the voltage multiplier in either of two different ways.

The terminal of the secondary 59 may be connected through the switch 75 and through the spark gap 77 to the point 79 on the resistor 19 of the voltage multiplier. The provision of the spark gap 77 prevents flow of current from the generator 1 at the given potential through the secondary coil 59 and the make-and-break device to ground. It will be understood that the generator 1, when continuously connected to the voltage multiplier across the ends of the resistors 19, 21, provides a constant potential, that is, the given potential across this multiplier. When, however, the circuit is closed by the makeand-break device 69, 73 a higher potential may be generated in the secondary 59 of the coil sufficient to discharge the secondaly 59 through the spark gap 77 and thereby to trigger the mutiplier for discharge in succession through the spark gaps 81, 23, 24, 25 and 26, thereby discharging the capacitors 11, 12, 13, 14, and 16 in series. To this end the spark gap 81 is connected across the respective terminals of the capacitors 11 and 12. The setting of the electrodes of the spark gap 77 and the ratio of the primary 57 and secondary 59 of the coil may be such that, when the circuit is closed and then opened at the make-and-break 69, 73, the spark gap 77 breaks down and the potential of the spark coil is applied to the terminal 79 of the multiplier so as to effect the requisite discharge in series through the connection 30 to the rotating arm 31 of the distributor for discharge to the spark plugs in succession. It will be understood that the form ofthe cam 71 and its angular relation upon the axis of the shaft 33 with respect to the distributor arm 31 are such that the circuit is broken at the fixed Contact 73 of the make-and-break device each time that the arm 31 is in spark gap relation to a fixed electrode 35.

The usual capacitor 83 is connected across the makeand-break contacts 69, 73 to control the sparking at these contacts.

As shown in Fig. 3 an alternative connection may be provided from the terminal of the secondary coil 59 to a selected point 85 on the resistor 21 of the voltage multiplier. This connection need not be provided with a spark gap as is the connection to the point 79 of the resistor 19 since it is made at the opposite side of the capacitors and spark gaps from the side at which the generator 1 is connected. It is made, however, at such a point that resistance 84 is interposed between the point 85 and ground to prevent excessive current flow to ground.

Switches 86 and 87 are shown as provided respectively in the connection from the secondary 59 through the spark gap 77 and in the alternative connection to the point 85 to provide for alternative use of these two means for effecting triggering discharge of the capacitors 11 to 16 inclusive by the potential of the secondary 59 of the coil. The ratio of the primary and secondary of the coil may be slightly modified in some cases to correspond to the potential of the point of connection 85 which is different from that of the point 79 at the instant of effecting discharge.

Fig. 4 shows a system in which the low voltage generator is omitted and the conventional spark coil of an automotive ignition system is replaced by a transformer, preferably somewhat modified as to the ratio of the primary and secondary windings. The primary 57 of the transformer is supplied from a battery 7, the secondary 59 of the transformer being connected through the rectifier 90 and resistance 91 to the end portion 51 of the resistor 19 to impress a unidirectional potential across the voltage multiplier. In this embodiment, a storage capacitor 93 is connected in parallel with the voltage multiplier and the potential developed in the secondary 59 of the transformer and impressed on the voltage multiplier also is applied to the capacitor 93. Having regard to the potential developed in the secondary 59 of the transformer, the capacitance of the capacitor 83 may be made sufiiciently large to provoke, when fully charged, discharge of the necessary amount of charge through the series connected capacitors of the voltage multiplier in the manner above described. Advantageously, the transformer has a magnetic core preferably providing a closed magnetic circuit and the primary 57 and secondary 59 are of such design as to be suitable for charging the capacitor 93 with suflicient charge at the given voltage, for example, not exceeding 5,000 volts.

The provision of the rectifier 90 disposed in the circuit as shown prevents discharge of the capacitor 93 to ground reversely through the secondary 59 of the transformer when the circuit is closed at the make-and-break device 69, 73. This make-and-break device actuated by the cam 71 and the distributor having the rotatable arm 31 and stationary electrodes 35 for distributing the charge to the spark plugs 36 upon discharge of the voltage multiplier are the same as described in connection with Figs. 1, 2 and 3.

In all of the embodiments shown in the drawings, a conventional spark advance mechanism 95 is provided for effecting angular displacement of the rotatable arm 31 of the distributor and the rotatable elements 41 and 45 of the synchronizing devices with respect to the driving connection from the engine crank shaft.

The embodiment of Fig. 4 also utilizes the auxiliary spark gap 77 connected to the point 79 on the voltage multiplier and the alternative connection to the point on the resistor 21 of the voltage multiplier, these connections respectively being selectively controlled by the switches 86 and 87 for triggering the voltage multiplier in the manner described in connection with Fig. 3.

It will be understood that according to either of the alternative embodiments of Fig. 4, the triggering of the voltage multiplier is effected concomitantly with operation of the makeand-break device 69, 73 to produce the oscillating current in the primary 57 of the transformer and the resultant potential across the secondary 59 which is rectified by the rectifier 90 to develop the charge in the capacitor 93 substantially at the given potential. Triggering may be effected directly from the rectifier 90 through the spark gap 77 or through the alternative connection to the point 85 of the resistor 21 upon selective operation of the switches 86 and 87.

The potential built up at the point of connection of the rectifier to the resistance 91 initially upon operation of the makeand-break device 69, 73 will be somewhat in excess of the potential across the capacitor 93 because of the resistance 91 and this excess may be suificient to effect triggering discharge, the spark gap 77 being suitably adjusted if discharge is to be effected through this spark gap. If desired, such operation may be carried out without utilizing the capacitor 93, but when the capacitor is connected across the voltage multiplier, the switch 97 then being closed, the resistance 91 not only serves to develop the excess potential just referred to for triggering discharge but also serves to control the flow of the current from the capacitor through the alternative connection to the point 85 and to ground. Thus the given potential is applied across the parallelly connected capacitors between the successive time periods in which the potential is built up and then discharge of the capacitors takes place upon operation of the make-and break device 69, 73. It will be understood, therefore,

11 that the capacitor 93 serves a function similar to that of the generator 1' ofFig. 1.

I claim:

1. In an ignition system, the combination with a source of given potential'and an ignition device operable at a substantially higher potential, of a plurality of capacitors connected in parallel across said source of given potential for charging said capacitors at said given potential, said parallely connected capacitors as a group being connected in series with said ignition device, a plurality of elements respectively connected between terminals of adjacent capacitors that respectively are connected to a given and to the other. side of said source and connecting said capacitors in series with each other, said elements being operable to effect discharge of said capacitors in series with each other and in' series with. said ignition device to develop said higher potential across said ignition device, and means connected to said parallely connected capacitors'and to saidelements for'limiting flow of'charge short circuiting said series-discharge of said capacitors through said elements to said ignition device.

2. in an ignition system the combination as defined in claim 1 in which said limiting means comprises a resistor connected in series with a selected side of said source of given potential, theterminals of said capacitors that are connected to said source at said selected side being connected at points on and spaced along said resistor.

3. in an ignition system, the combination with a source of given potential and an ignition device operable at a substantially higher potential, of a plurality of capacitors connected in parallel across said source of given potential for charging said capacitors at said given potential, said parallely connected capacitors as a group being connected in series with said'ignition device, a plurality of spark gap elements each having a terminal connected to the terminal of a capacitor that is connected to a given side of said source and having another terminal connected to the terminal of another capacitor that is connected to the other side of said source to connect said capacitors in series and for discharge of said capacitors in series through said spark gap elements and through said ignition device, and means connected to said capacitors and to said sparkgap elements for limiting flow of charge short circuiting said series discharge through said capacitors.

4. in an ignition sysem the combination as defined in claim 3' which comprises a resistor connected in series with a selected side of said source of given potential, the terminals of said capacitors that are connected to said source at said selected side being connected at points on and spaced along said resistor, the terminals of said spark gap elements that are connected to' said selected side of said source being connected to said resistor adjacent the respective points of connection of said capacitors to said resistor.

5. in an ignition system, the combination with a source of given potential and an ignition device operable at a substantially higher potential, of a plurality of capacitors connected in parallel across said source of said given potential for charging said capacitors at said given potential, said parallelly connected capacitors as a group being connected in series with said ignition device, a plurality of means respectively connected between terminals of adjacent capacitors that are respectively connected to a given and to the other side of said source and connecting said capacitors in series with each other, said means being operable to effect discharge of said capacitors in series with each other and in series with said ignition device to develop said higher potential across said ignition device, an auxiliary capacitor connected in parallel with said other capacitors across said source of given potential, and a circuit closing device connected between the terminal otone of said other capacitors that-is connected to said given side of said source and the terminal of said auxiliary capacitor that is connected to said other side of said source so as to connect said circuit closing device" in series with all said capacitors for initiating the series connection of said capacitors upon closing of the circuit through said circuit closing device.

6. In an ignition system, the combination with a source of given potential, a plurality of ignition devices operable at a substantially higher potential, and a distributor'having a plurality of electrodes in spaced relation to each other along a given path of movement and respectively connected to said ignition devices, said distributorhaving member movable along said path successively into cir cuit closing relation to said electrodes for establishingin succession connection of the respective ignition devices to said member, of a plurality of capacitors connected in parailel across said source of given potential for charging" capacitors at said given potential, said capacitors as a group being connected in series with said movable member of said distributor, a plurality of spark gap-ele ments having respective terminals connected to the'terminals of respective capacitors that are connected to a given side of said source and having their respective other" terminals connected to respective terminals of said capacitors that are connected to the other side of said source so that said capacitors are connected in series with said spark gap elements for discharge of said capacitors in series through said spark gap elements to said movable said auxiliary electrodes being connected together and-asa group connected to a selected side of said source of given potential adjacent the terminal of one of said'capacitors connected to said selected side, and a circuitclosi-ng element movable along said predetermined path in succession into circuit closing relation to said auxiliary electrodes and connected to the side of said source oppositeto said selected side and adjacent the terminalof said auxiliary capacitor connected to said opposite. side, said:

series connection of said capacitors being established through said auxiliary capacitor concomitantly with:clos+ ing of the circuit in the respective circuit, closingpositions of said circuit closing element with respect to said auxiliary electrodes.

7. In an ignition system, the combination as defined.

in claim 6 which comprises a plurality of: sets of) said auxiliary electrodes, the auxiliary electrodes in each:set being disposed in spaced relation along respectively predetermined paths, and a plurality of said circuit closing elements respectively movable along the respective paths into circuit closing relation to the auxiliary electrodes in succession in the respective paths.

8. In an ignition system the combination with a source of low potential, a transformer connected to said source of low potential and operable to produce a given potential greater than said low potential, and an ignition device operable at a potential substantially higher than said given potential, of a plurality of capacitors connected in parallel, said parallelly connected capacitors as a group being connected in series with said ignition device and in series with said transformer, a plurality of discharge elements each connected between a given terminal of a capacitor that is at a given side of said parallelly connected capacitors and the terminal of the adajacent capacitor that is at the opposite side of said parallelly connected capacitors from said given terminal, said elements being operable to eifect connection of said capacitors in series with each other and discharge of said capacitors in series with each other and in series with said ignition device to develop said higher potential across said ignition device upon operation of said transformer to produce said given potential, means for charging said parallelly connected capacitors substantially at said given potential, andmeans connected to said capacitors for limiting flow of charge short circuiting said series discharge of said capacitors through said discharge elements and said ignition device.

9. In an ignition system, the combination as defined in claim 8 in which said source of low potential is a direct current source, said transformer having a low potential primary coil and having a secondary coil capable of developing said given potential upon energizing said primary coil at said low potential, a make-and-break device connected in series with said primary coil of said transformer and with said low potential source for intermittently energizing said primary coil intermittently to develop in said secondary coil said given potential, said parallelly connected capacitors as a group being connected in series with said secondary coil of said transformer for intermittently charging said parallelly connected capacitors at said given potential and for effecting discharge of said capacitors in series with each other and in series with said ignition device to develop said higher potential across said ignition device concomitantly with operation of said make-and-break device.

10. In an ignition system, the combination as defined in claim 9 which comprises a resistance connected in series with said primary coil of said transformer and said makeand-break device for reducing said given potential.

11. In an ignition system, the combination as defined in claim 9 which comprises an auxiliary discharge device connected in series with said secondary winding of said transformer for discharge of said secondary winding to said parallelly connected capacitors through said auxiliary discharge device.

12. In an ignition system, the combination as defined in claim 11 which comprises a connection in parallel with said auxiliary discharge device and at least one of said series connected discharge elements, and means selective- 1y operable to discharge said secondary winding through said auxiliary discharge device and through said parallel connection.

13. In an ignition system, the combination as defined in claim 8 which comprises a rectifier connected in series with said parallelly connected capacitors across said given potential of said transformer for developing said given potential as a unidirectional potential across said parallelly connected capacitors.

14. In an ignition system, the combination as defined in claim 13 which comprises a storage capacitor connected across said parallelly connected capacitors for storing the charge delivered by said rectifier.

15. In an ignition system, the combination as defined in claim 13 which comprises a resistor connected in series with said rectifier and with said parallelly connected capacitors.

16. In an ignition system, the combination as defined in claim 8 in which said means for charging said parallelly connected capacitors comprises a direct current generator connected in parallel across said capacitors.

17. In an ignition system, the combination with a source of given potential, and an ignition device operable at a substantially higher potential, of two resistors respectively connected to the terminals of said source of given potential, a plurality of capacitors in a group connected in parallel with each other between said resistors respectively at points spaced along said resistors, said ignition device having one terminal thereof connected to the terminal of an end capacitor of said group which is connected to one of said resistors, the other terminal of said ignition device being connected to the terminal of the other end capacitor of said group which is connected to the other resistor, a plurality of spark gap elements having terminals thereof connected respectively to the terminals of said capacitors that are connected to a given one of said resistors and having their other terminals respectively connected to the terminals of the successively adjacent capacitors that are connected to the other resis- 14 tor to connect said capacitors in series, means connected to said capacitors for charging said capacitors in parallel, and means connected to said capacitors and operable to effect discharge of said capacitors in series through said spark gap elements in series to said ignition device.

18. In an ignition system, the combination with a source of given potential and an ignition device operable at a substantially higher potential, of a plurality of capacitors connected in parallel with each other across said source of given potential, charge flow limiting means in the respective connections between given terminals of said capacitors, charge flow limiting means in the respective connections between the other terminals of said capacitors, a plurality of spark gap elements respectively having terminals connected to the respective given terminals of said capacitors and having their other terminals respectively connected to said other terminals of other capacitors of said plurality of capacitors so as to connect said capacitors in series through said spark gap elements for effecting flow of charge of said capacitors in series with each other through said spark gap elements upon dis charge of said spark gap elements, said charge flow limiting means being operable concomitantly with said flow of charge in series through said capacitors and through said spark gaps for limiting short circuiting of said series flow through said spark gaps and said capacitors, said capacitors as a group being connected in series with said ignition device, and means for initiating discharge of said capacitors in series through said capacitors and through said ignition device.

19. In an ignition system, the combination with a unidirectional source of given potential, an ignition device operable at a substantially higher potential, and an ignition circuit closing device connected in series with said ignition device and operable to close the circuit of said ignition device, of a plurality of capacitors connected in parallel across said unidirectional source of given potential for charging said capacitors at said given potential, said parallelly connected capacitors as a group being connected in series with said ignition circuit closing device and said ignition device, means connecting said capacitors in series with each other, said means being operable to effect discharge of said capacitors in series with each other and in series with said ignition device concomitantly with closing operation of said ignition circuit closing device to develop said higher potential across said ignition device, an auxiliary capacitor connected in parallel with said other capacitors across said source of given potential, an auxiliary circuit closing device connected between the terminal of one of said other capacitors that is connected to a given side of said source and the terminal of said auxiliary capacitor that is connected to the other side of said source so as to connect said auxiliary circuit closing device in series with all said capacitors, and means operatively connecting said auxiliary circuit closing device to said ignition circuit closing device for effecting the closing operation of said auxiliary circuit closing device concomitantly with the circuit closing operation of said ignition circuit closing device for initiating the series discharge of said capacitors upon closing of said circuit through said auxiliary circuit closing device.

20. In an ignition system, the combination with a source of unidirectional potential, a transformer having a low potential coil and a high potential coil, a makeand-break device, said make-and-break device being connected in series with said source through the low potential coil of said transformer, an ignition device, an ignition circuit closing device connected in series with said ignition device and operable to close the circuit of said ignition device, and means operatively connecting said make-and-break device to said ignition circuit closing device for operating said devices in predetermined relation to each other for energizing said low potential coil of said transformer concomitantly with the circuit closing operation of said ignition circuit closing device, of a plurality of capacitors connected in parallel, said parallelly connected capacitors as a group being connected in series with ignition circuit closing device and with said ignition device, said parallelly connected capacitors being connected in parallel across a unidirectional source of a given potential for charging said capacitors at said given potential, a plurality of means respectively connected between adjacent capacitors and connecting said capacitors in series with each other, said means being operable to effect discharge of said capacitors in series with each other 10 and in series with said ignition circuit closing device and said ignition device to develop an ignition potential across said ignition device, said parallelly connected capacitors as a group being connected in series with said high potential coil of said transformer for triggering said dischargeof said capacitors through said ignition circuit closing device-and saidignitiondevice upon operation of said make*and-breakdevice.

References Cited in the file of this patent UNITED STATES PATENTS 2,099,327 Brasch et a1 Nov. 16, 1937 2,119,588 Lindenbald June 7, 1938 2,221,573 Bruckmann Nov. 12, 1940 2,285,322 Anderson June 2, 1942 2,447,832 Abend et al Aug. 24, 1948 2,456,475 Wargin et a1 Dec. 14, 1948 2,571,788' Tognola Oct. 16, 1951 UNITED STATES PATENT OFFICE CERTIFICATE OF CORRECTION Patent No, 2,835,850 May 20, 1958 Roger Morel It is hereby certified that error appears in the -printed specification of the above numbered patent requiring correction and that the said Letters Patent should read as corrected below.

Column 2, line 72, for capaictors read capacitors column 3, line 45, for "igniton read e ignition column 12, line 67, for adajaoent' read me adjacent column 15, line 3, for 'With ignition" read with. said ignitio J=--=".,

Signed. and sealed this 7th day of October 1958.

SEAL uest? KARL H. AXLINE Attcsting ()flicer ROBERT C. WATSON Commissioner of Patents 

